Of late, to clean an exhaust gas from an internal combustion engine, an ignition position of the internal combustion engine is required to be controlled at optimum. In case that an ignition system for the internal combustion engine is of contactless type, an ignition signal generating device for the ignition system is provided with an electronic advancing circuit. A conventional ignition signal generating device has a disadvantage of no possibility of optionally determining the advance width of the ignition position and also a disadvantage of a complicated construction of the ignition signal generating circuit because of a revolution detector required.
Even a complicated characteristic is required in which the ignition position is advanced in phase in a two stepped manner relative to the revolution of the internal combustion engine. However, such a complicated characteristic cannot be obtained by the conventional ignition signal generating device.